Annals of Neurology
September 22, 2016
Silvia Casarotto, Angela Comanducci, Mario Rosanova et al.
504 citations
A brain-based measure called the Perturbational Complexity Index (PCI) can reliably distinguish conscious from unconscious individuals, even when they cannot speak or move. The index was first validated in 150 healthy and brain-injured people who could report their conscious state, achieving perfect accuracy in separating conscious from unconscious conditions. Applied to 81 noncommunicative patients, PCI correctly identified 94.7% of those in a minimally conscious state and revealed that 9 of 43 patients diagnosed as vegetative had PCI values overlapping with conscious individuals. These findings suggest that some behaviorally unresponsive patients may retain hidden conscious capacity.
Nature Communications
February 25, 2022
Minji Lee, Leandro Sanz, Alice Barra et al.
120 citations
A deep-learning-based explainable consciousness indicator (ECI) uses EEG responses to transcranial magnetic stimulation and resting-state EEG to separately quantify arousal and awareness. Tested during sleep (n=6), general anesthesia (n=16), and severe brain injury (n=34), ECI distinguishes states such as ketamine-induced anesthesia and rapid eye movement sleep, which combine low arousal with high awareness. Parietal brain regions are most relevant for these measurements. The indicator offers a way to disentangle the two components of consciousness across physiological, pharmacological, and pathological conditions.
Frontiers in Systems Neuroscience
August 14, 2019
Vincent Bonhomme, Cécile Staquet, Javier Montupil et al.
109 citations
General anesthesia reversibly alters consciousness without globally shutting down the brain. Depending on the agent and dose, it can produce a complete absence of subjective experience (unconsciousness), a conscious experience without environmental perception (disconnected consciousness, like during dreaming), or oriented consciousness with environmental awareness (connected consciousness). Each state may be followed by explicit or implicit memories. Progress in brain function exploration has improved understanding of neural correlates of consciousness and their alterations during anesthesia, including changes in functional and effective brain connectivity, consciousness network topology, and spatio-temporal dynamics.
Brain Injury
August 1, 2014
Martino Napolitani, Olivier Bodart, Paola Canali et al.
44 citations
Transcranial magnetic stimulation combined with high-density electroencephalography (TMS-hdEEG) offers advantages over other brain imaging techniques for assessing consciousness. A key requirement for consciousness is the brain's capacity to rapidly integrate information across specialized cortical areas. TMS-EEG stimulates any cortical area and records immediate electrical responses, successfully measuring changes in brain complexity under physiological, pharmacological, and pathological conditions. This technique reliably discriminates between conscious and unconscious patients at the single subject level, though further validation as a clinical tool is needed.